Liquid crystal display device with two kinds of projected portions on a substrate

ABSTRACT

A liquid crystal display device includes first and second substrates, a liquid crystal layer sandwiched between the first and second substrates, a pixel electrode formed on the first substrate, and a counter electrode formed on the second substrate. A plurality of projected portions are formed on the second substrate in a pixel area. The plurality of projected portions includes a first projected portion and a second projected portion, and the first projected portion is longer than the second projected portion in the pixel area.

This application is a continuation application of U.S. application Ser.No. 09/542,870 filed on Apr. 4, 2000 now U.S. Pat. No. 6,583,846.

BACKGROUND OF THE INVENTION

The present invention relates to a liquid crystal display device, andparticularly to a liquid crystal display device provided with spacerssandwiched between a pair of opposing substrates with a liquid crystallayer interposed therebetween.

Placement of spacers between a pair of opposing substrates with a liquidcrystal layer therebetween can establish a uniform thickness of theliquid crystal layer and thereby prevent occurrence of non-uniformity ina displayed image.

Beads, for example, are used as spacers. Initially beads are dispersedon a surface of one of a pair of substrates facing toward a liquidcrystal layer, and then the other of the pair of substrates isoverlapped over the one of the pair. But the surfaces of the substratesare uneven, some spacers are positioned in indented portions in thesurfaces of the substrates, others are positioned in raised portions inthe surfaces in the substrates, and consequently, the desired spacingbetween the pair of substrates are not sometimes obtained.

There is another type of spacers which are fixed at predeterminedpositions on a surface of one of a pair of substrates facing toward aliquid crystal layer before the other of the pair of substrates isoverlapped over the one of the pair. The spacers are formed only onindented portions in the uneven substrate, for example, andconsequently, the desired spacing between the pair of substrates isobtained.

Spacers are disclosed in Japanese Patent Application Laid-open No. Hei8-76131 (laid-open on Mar. 22, 1996), Japanese Patent ApplicationLaid-open No. Hei 8-114809 (laid-open on May 7, 1996) and JapanesePatent No. 2,907,137 (registered on Apr. 2, 1999).

SUMMARY OF THE INVENTION

The spacers of the above-explained type having the spacers fixed on asubstrate have the above advantage and can also improve the displayquality further by optimizing the arrangement of the spacers.

The present invention has been made in this situation, and the purposeof the present invention is to provide a liquid crystal display devicehaving the quality of a displayed image improved.

The representative ones of the inventions disclosed in thisspecification can be summarized as follows.

To accomplish the above object, in accordance with an embodiment of thepresent invention, there is provided a liquid crystal display devicecomprising: a pair of opposing substates, at least one of said pair ofopposing substrates being transparent, a liquid crystal film sandwichedbetween said pair of opposing substates, a plurality of elactrodes of afirst kind disposed on an inner surface of one of said pair of opposingsubstrates for defining a plurality of pixels, at least one electrode ofa second king disposed on an inner surface of one of (1) said one ofsaid pair of opposing substrates so as to be adjacent to, but spacedfrom said plurality of electrodes of said first kind and (2) another ofsaid pair of opposing substrates so as to face said plurality ofelectrodes of said first kind, and at least one spacer disposedapproximately at a center of at least one of said plurality of pixelsfor establishing a spacing between said pair of opposing substrates,said at least one spacer being fixed to one of said pair of opposingsubstrates and covered with one of (1) a corresponding one of saidplurality of electrodes of said first kind and (2) a corresponding oneof said at least one electrode of said second kind.

To accomplish the above object, in accordance with anther embodiment ofthe present invention, there is provided a liquid crystal display devicecomprising: a pair of opposing substrates, at least one of said pair ofopposing substrates being transparent, a liquid crystal film sandwichedbetween said pair of opposing substrates, a plurality of electrodes of afirst kind disposed on an inner surface of one of said pair of opposingsubstrates for defining a plurality of pixels, at least one electrode ofa second kind disposed on an inner surface of one of (1) said one ofsaid pair of opposing substrates so as to be adjacent to, but spacedfrom said plurality of electrodes of said first kind and (2) another ofsaid pair of opposing substrates so as to face said plurality ofelectrodes of said first kind, and at least one spacer disposedapproximately at a center of at least one of said plurality of pixelsfor establishing a spacing between said pair of opposing substrates,said at least one spacer being fixed to one of said pair of opposingsubstrates and covered with one of (1) a corresponding one of saidplurality of electrodes of said first kind and (2) a corresponding oneof said at least one electrode of said second kind, and another of saidcorresponding one of said plurality of electrodes of said first kind andsaid corresponding one of said at least one electrode of said secondkind being patterned so as not to face said at least one spacer.

To accomplish the above object, in accordance with still an embodimentof the present invention, there is provided a liquid crystal displaydevice comprising: a pair of opposing substrates, at least one of saidpair of opposing substrates being transparent, a liquid crystal filmsandwiched between said pair of opposing substrates, a plurality ofelectrodes of a first kind disposed on an inner surface of one of saidpair of opposing substrates for defining a plurality of pixels, aplurality of wiring lines of a first kind coupled to said plurality ofelectrodes of said first kind, at least one electrode of a second kinddisposed on an inner surface of one of (1) said one of said pair ofopposing substrates so as to be adjacent to, but spaced from saidplurality of electrodes of said first kind and (2) another of said pairof opposing substrates so as to face said plurality of electrodes ofsaid first kind, at least one wiring line of a second kind coupled tosaid at least one electrode of said second kind, and at least one spacerdisposed approximately at a center of at least one of said plurality ofpixels for establishing a spacing between said pair of opposingsubstrates, said at least one spacer being fixed to one of said pair ofopposing substrates and covered with one of (1) a corresponding one ofsaid plurality of electrodes of said first kind and (2) a correspondingone of said at least one electrode of said second and said at least onespacer being disposed so as to face one of (1) said plurality of wiringlines of said first kind and (2) said at least one wiring line of saidsecond kind.

In the liquid crystal display device employing a spacer covered with anelectrode, directions of electric fields generated between the side wallof the spacer and another electrode are different from directions ofelectric fields generated by the electrode and the another electrode inthe remaining region of one pixel associated with the spacer, andconsequently, the so-called “multi-domain” effect is produced in theregion in the vicinity of the side wall. The reversal in transmittedlight intensity through the liquid crystal layer occurs at viewingangles deviating considerably from the main anticipated viewing angledue to the angular dependence of the electro-optic characteristics ofthe liquid crystal layer. The so-called multi-domain effect is thatobtained by subdividing one pixel into a plurality of regions providedwith different angular dependence of the electro-optic characteristicsto reduce the angular dependence of the one pixel as a whole and therebyto eliminate or reduce the above-mentioned reversal in transmitted lightintensity.

And in the liquid crystal display device of the horizontal electricfield type described subsequently, the optimum arrangement of spacers issecured.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, in which like reference numerals designatesimilar components throughout the figures, and in which:

FIG. 1A is a plan view of a pixel in a liquid crystal display device inaccordance with an embodiment of the present invention, and FIG. 1B is across-sectional view of the pixel taken along line b—b of FIG. 1A;

FIG. 2 is an illustration of an arrangement of main chains in an exampleof liquid crystal orientation film used in a liquid crystal displaydevice of the present invention before being subjected to a rubbingtreatment;

FIG. 3 is an illustration of an arrangement of main chains in theexample of the liquid crystal orientation film of FIG. 2 after havingbeen subjected to a rubbing treatment;

FIG. 4A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 4B is a cross-sectional view of the pixel taken along line b—b ofFIG. 4A;

FIG. 5 is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 6A is a plan view of an intersection of a gate line and a drainline with an insulating film interposed therebetween for explaining aproblem with the intersection, and FIG. 6B is a cross-sectional view ofthe intersection taken along line b—b of FIG. 6A;

FIG. 7 is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 8A is a plan view of a thin film transistor for explaining aproblem with the thin film transistor, and FIG. 8B is a cross-sectionalview of the thin film transistor taken along line b—b of FIG. 8A;

FIG. 9 is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 10 is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 11A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 11B is a cross-sectional view of the pixel taken along line b—b ofFIG. 11A;

FIG. 12A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 12B is a cross-sectional view of the pixel taken along line b—b ofFIG. 12A;

FIG. 13A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 13B is a cross-sectional view of the pixel taken along line b—b ofFIG. 13A;

FIG. 14A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 14B is a cross-sectional view of the pixel taken along line b—b ofFIG. 14A;

FIG. 15 is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 16 is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 17A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 17B is a cross-sectional view of the pixel taken along line b—b ofFIG. 17A;

FIG. 18A is a plan view of a pixel in a liquid crystal display device inaccordance with still another embodiment of the present invention, andFIG. 18B is a cross-sectional view of the pixel taken along line b—b ofFIG. 18A;

FIG. 19 is a plan view of an example of a spacer used in a liquidcrystal display device of the present invention;

FIG. 20 is a plan view of the spacer of FIG. 19 for explaining anadvantage provided by the spacer;

FIG. 21 is a fragmentary perspective view of a liquid crystal displaydevice in accordance with still another embodiment of the presentinvention;

FIG. 22 is a plan view of a liquid crystal display device in accordancewith still another embodiment of the present invention;

FIG. 23 is a perspective view of another example of a spacer used in aliquid crystal display device of the present invention;

FIG. 24 is a perspective view of still another example of a spacer usedin a liquid crystal display device of the present invention;

FIG. 25 is a cross-sectional view of a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 26 is a cross-sectional view of a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 27 is a cross-sectional view of a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIG. 28A is a plan view of a liquid crystal display device in accordancewith still another embodiment of the present invention, and FIG. 28B isa plan view of a liquid crystal display device in accordance with stillanother embodiment of the present invention;

FIG. 29 is a cross-sectional view of a liquid crystal display device inaccordance with still another embodiment of the present invention;

FIGS. 30A to 30E illustrate the steps of an exemplary method ofmanufacturing the liquid crystal display device of FIG. 29;

FIGS. 31A to 31E illustrate the steps of another exemplary method ofmanufacturing the liquid crystal display device of FIG. 29;

FIG. 32 is a cross-sectional view of a liquid crystal display device inaccordance with still another embodiment of the present invention; and

FIG. 33 is a cross-sectional view of a liquid crystal display device inaccordance with still another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the liquid crystal display device according to thepresent invention will be explained by reference to the drawings.

Embodiment 1

FIGS. 1A and 1B illustrate a configuration of an embodiment of theliquid crystal display device according to the present invention. FIG.1A is a plan view of one of a plurality of pixels in a liquid crystaldisplay device of the so-called horizontal electric field type, FIG. 1Bis a cross-sectional view of the pixel of FIG. 1A taken along line b—bof FIG. 1A.

The pixels as illustrated in FIGS. 1A and 1B are arranged in the form ofa matrix to constitute a display area.

In the liquid crystal display device of the horizontal electric fieldtype (commonly called the in-plane switching (IPS) type), thetransmission of light at each pixel is controlled by a horizontalelectric field applied in parallel with a layer of liquid crystalmaterial sandwiched between opposing transparent electrodes formed onthe inner surfaces of the opposing transparent substrates. Each pixel isformed by two electrodes formed on one of a pair of opposing substrates.For the purpose of device construction and operation, U.S. Pat. No.5,598,285, issued to Kondo et al. on Jan. 28, 1997, is herebyincorporated by reference.

On a surface on a liquid crystal layer side of one of a pair of opposingtransparent substrates sandwiching the liquid crystal layer, a scanningsignal line (a gate line) 2 extends in the x direction in FIG. 1A and ismade of a chromium film, for example. As shown in FIG. 1A, the gate line2 is disposed below the pixel area, for example, to maximize theeffective area of the pixel. The gate line 2 is supplied with a gatesignal from a circuit external to the display area so as to drive a thinfilm transistor TFT described subsequently.

Approximately at the center of the pixel area, a counter-voltage signalline 4 extends in the x direction in FIG. 1A and is made of the samematerial as the gate line 2, for example. A plurality (three, forexample) of counter electrodes 4A made integrally with thecounter-voltage signal line 4 extend in a direction perpendicular to thecounter-voltage signal line 4, i. e. ±y direction, for example.

The counter electrodes 4A are supplied with a signal serving as areference voltage for a video signal supplied to a pixel electrode 5subsequently described via the counter-voltage signal line 4, so as togenerate an electric field of the strength corresponding to the videosignal between the pixel electrode 5 and the counter electrodes 4A.

The generated electric field contains a component parallel with themajor surface of the transparent substrate 1 and this component controlslight transmission through the liquid crystal layer. This type of theliquid crystal display device uses a component of an electric field inparallel with the major surface of the transparent substrate 1, and itis this reason that this type is called the horizontal electric fieldtype. The counter-voltage signal line 4 is supplied with a referencevoltage from a circuit external to the display area.

After the gate lines 2 and the counter-voltage signal lines 4 have beenformed on the transparent substrate 1, an insulating film INS made ofsilicon nitride, for example, is formed on the surface of thetransparent substrate 1 including the gate lines 2 and thecounter-voltage signal lines 4.

The insulating film INS serves as a gate insulating film in an areaformed with a thin film transistor TFT described subsequently, serves asan interlayer insulating film between the gate lines 2 and thecounter-voltage signal lines 4 in an area formed with video signal lines(drain lines) 3 described subsequently, and serves as a dielectric filmin an area formed with a capacitor Cadd described subsequently.

In the area formed with the thin film transistor TFT, a semiconductorlayer 6 made of amorphous Si, for example, is disposed to overlap withthe gate line 2 to form the thin film transistor TFT in conjunction withthe gate line 2.

A drain electrode 3A and a source electrode 5A are disposed on the topof the semiconductor layer 6 to form the thin film transistor TFT of theso-called inverted staggered structure by using a portion of the gateline 2 as a gate electrode. The drain electrode 3A and the sourceelectrode 5A are formed on the semiconductor layer 6 together with thepixel electrode 5 simultaneously with formation of the drain line 3, forexample.

That is to say, in FIG. 1A, the drain line 3 is formed to extend in they direction, and the drain electrode 3A formed integrally with the drainline 3 is disposed on the semiconductor layer 6.

The drain line 3 is disposed to the left of the pixel area, for example,to maximize the effective pixel area, as shown in FIG. 1A.

The source electrode 5A is formed simultaneously with the drain line 3and integrally with the pixel electrode 5.

The pixel electrode 5 is formed to extend between the two adjacentcounter electrodes 4A in the y direction in FIG. 1A. In other words, thetwo counter electrodes 4A are disposed on opposite sides of the pixelelectrode 5, and are spaced approximately equal distances from the pixelelectrode 5 so as to generate electric fields between the pixelelectrode 5 and the counter electrodes 4A. A portion of the pixelelectrode 5 facing the counter-voltage signal line 4 is configured so asto increase its area and to form a capacitor Cadd by using theinsulating film INS as a dielectric.

The capacitor Cadd serves to store a video signal supplied to the pixelelectrode 5, for example, for a comparatively longer time. The thin filmtransistor TFT is turned on by a scanning signal supplied from the gateline 2, a video signal from the drain line 3 is supplied to the pixelelectrode 5 via the thin film transistor TFT, and then after the thinfilm transistor TFT is turned off, the video signal having been suppliedto the pixel electrode 5 is stored in the capacitor Cadd.

Then, a protective film PAS made of silicon nitride, for example, isformed over the entire surface of the thus processed transparentsubstrate 1 such that the thin film transistor TFT, for example, canavoid direct contact with the liquid crystal layer. An orientation film7 is formed on the protective film PAS so as to determine the directionof initial orientation of the liquid crystal molecules.

The thus processed transparent substrate is called the TFT substrate 1A.A liquid crystal panel is completed by superposing the TFT substrate 1Aon a transparent substrate called the filter substrate 1B with a liquidcrystal layer interposed therebetween such that the orientation film 7of the TFT substrate 1A is in contact with the liquid crystal layer.

A black matrix BM is formed on the surface of the filter substrate 1B onthe liquid crystal-layer side thereof for defining the contour of thepixel area as indicated in FIG. 1A, a color filter FIL is formed in theopening (a central portion of the pixel area excluding its periphery) inthe black matrix BM, and a planarizing film 8 is formed on the surfaceof the transparent substrate 1B including the black matrix BM and thecolor filter FIL.

A spacer 10 is formed on the planarizing film 8 such that the spacer 10is superposed on the approximately central portion of the area formingthe capacitor Cadd. The spacer 10 is formed by coating synthetic resin,for example, on the planarizing film 8 and then by patterning thesynthetic resin layer by a photolithography technique (and also byselective etching, if necessary). The height of the spacer 10 controlsthe spacing between the TFT substrate 1A and the filter substrate 1Bsandwiching the liquid crystal layer.

The reason why the spacer 10 is superposed on the capacitor Cadd is thatthe width of the counter-voltage signal line 4 lying below it is madecomparatively wider than that of the other signal lines, andconsequently, an area of the orientation film 11 suffering fromorientation defects caused by the spacer 10 explained later is preventedfrom passing light through the area by the counter-voltage signal line4. Another reason is that the spacer 10 is positioned at anapproximately center of the pixel area surrounded by the black matrixBM, thereby it becomes easier to control the thickness of the liquidcrystal layer (the spacing between the two substrates) in the pixel.

After the spacers 10 having been formed on the filter substrate 1B, theorientation 11 is formed on the surface of the filter substrate 1Bincluding the spacers 10 as shown in FIG. 1B.

The orientation film 11 is fabricated by coating synthetic resin, forexample, on the planarizing film 8 and then rubbing the synthetic resinfilm. It is inevitable that orientation defects in the orientation film11 is caused around the vicinity of the spacer 10 by rubbing thesynthetic resin film. But the area suffering from the orientationdefects is prevented sufficiently from passing light through the area bythe light-blocking counter-voltage signal line 4 as explained above.

In the above embodiment, the spacer 10 is formed to be superposed on thecapacitor Cadd, but the present invention is not limited to thisarrangement. When the capacitor Cadd is of the comparatively small size,the spacer 10 may be formed to be superposed on a portion of thecounter-voltage signal line 4 displaced from the capacitor Cadd. In thiscase, the spacer 10 may be superposed on a different signal line, forexample, which traverses the pixel area.

In the above embodiment, the spacer 10 is formed on the filter substrate1B, but the spacer 10 may be formed on the TFT substrate 1A. Thisarrangement provides an advantage that the spacer 10 is positionedaccurately with respect to the counter-voltage signal line 4.

Embodiment 2

This embodiment explains the concrete configurations of the orientationfilms 7, 11 in the liquid crystal display device of Embodiment 1.

The rubbing directions of the orientation films 7, 11 correspond to thedirections of the initial orientations of liquid crystal molecules, andthe orientation films 7 and 11 of the TFT substrate 1A and the filtersubstrate 1B, respectively, are rubbed in the same direction, in otherwords, the directions of the initial orientations of the orientationfilms 7 and 11 are parallel with each other.

In the area formed with the spacer 10, the orientation film 11 formed onthe top of the spacer 10 contacts the orientation film 7 formed on thefilter substrate 1A, and it was confirmed that adhesion at the contactarea is increased.

In the synthetic resin film before being rubbed, main chains of thematerial are randomly arranged as illustrated in FIG. 2, for example,but in the synthetic resin film rubbed in the direction as described,main chains of the material are arranged in one direction andconsequently, the orientation films 7, 11 are bonded together firmly bythe intermolecular force.

It was experimentally confirmed that, when benzene rings are containedin the structure of molecules of the orientation film, theabove-mentioned adhesion at the contact area is further increased.

It was also confirmed that the above-mentioned adhesion at the contactarea is still further increased when a material having a greater numberof main chains than that of side chains is chosen for the orientationfilm.

Materials satisfying this condition for the orientation film are asfollows:

The orientation film is composed of a polyimide resin film of 50 nm inthickness and made from 2,2-bis[4-(p-aminophenoxy) phenylpropane] andpyromellitic dianhydride, for example.

For other materials for the orientation film, amines to be copolymerizedwith tetracarboxylic acid dianhydride are as follows:

-   -   phenylene diamime, diphenylene diamine, triphenylene diamine, a        compound represented by the formula below,        where X denotes a direct coupling, —O—, —CH₂—, —SO₂—, —CO—,        —CO₂—, or —CONH—, or compounds having a structure represented by        one of the formulas below,        where X denotes a direct coupling, a compound of        bis(aminophenoxy)diphenyl, for example.

The following are specific examples: p-phenylenediamine,m-phenylenediamine, 4,4′-diaminoterphenyl, 4,4′-diaminodiphenylsulfone,3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylbenzoate,4,4′-diaminodiphenylmethane, 2,2′-(4,4′-diaminodiphenyl) propane,4,4′-bis (p-aminophenoxy) diphenylsulfone,4,4′-bis(m-aminophenoxy)diphenylsulfone,4,4′-bis(p-aminophenoxy)diphenylether,4,4′-bis(P-aminophenoxy)diphenylketone,4,4′-bis(P-aminophenoxy)diphenylmethane,2,2′-[4,4′-bis(p-aminophenoxy)diphenyl]propane.

Also 4,4′-diamino-3-carbamoyldiphenylether represented by the formulabelow,

or diaminopolysiloxane represented by the formulas below,

can be used.

The exemplary diamines to be copolymerized with tetracarboxylic aciddianhydride, but not containg halogen radicals are as follows:

-   -   4,4′-diaminodiphenylether-3-carbonamide,        3-3′-diaminodiphenylsulfone, 3-3′dimethyl        4-4′diaminodiphenylether, 1,6-diaminohexane,        2-2′-bis[4-(4-aminophenoxy)diphenyl]propane,        2-2′-bis[4-(4-aminophenoxy)phenyl]methane,        2-2′-bis[4-(4-aminophenoxy)phenyl]sulfone,        2-2′-bis[4-(4-aminophenoxy)phenyl]ketone,        2-2′-bis[4-(4-aminophenoxy)phenyl]biphenyl,        2-2′-bis[4-(4-aminophenoxy)phenyl]cyclohexane,        2-2′-bis[4-(4-aminophenoxy)phenyl]methylcyclohexane,        bis[4-(4-aminobenzoyloxy)benzoic]propane,        bis[4-(4-aminobenzoyloxy)benzoic]cyclohexane,        bis[4-(4-aminobenzoyloxy)benzoic]methylcyclohexane,        bis[4-(4-aminomethylbenzoyloxy)benzoic]propane,        bis(4-aminobenzoyloxy)propane, bis(4-aminobenzoyloxy)methane,        bis[2-(4-aminophenoxy)phenyl]methane,        bis[2-(4-aminophenoxy)-3,5-dimethylphenyl]methane,        bis[2-(4-aminophenoxy)-3,4,5-trimethylphenyl]methane,        bis[2-(4-aminophenoxy)-3,5,6-trimethylphenyl]methane,        bis[2-(4-aminophenoxy)-3,5-diethylphenyl]methane,        bis[2-(4-aminophenoxy)-5-n-propylphenyl]methane,        bis[2-(4-aminophenoxy)-5-isopropylphenyl]methane,        bis[2-(4-aminophenoxy)-5-methyl 3-isopropylphenyl]meethane,        bis[2-(4-aminophenoxy)-5-n-butylphenyl]methane,        bis[2-(4-aminophenoxy)-5-isobutylphenyl]methane,        bis[2-(4-aminophenoxy)-3-methyl 5-t-butylphenyl]methane,        bis[2-(4-aminophenoxy)-5-cyclohexylphenyl]methane,        bis[2-(4-aminophenoxy)-3-methyl-5-cyclohexylphenyl]methane,        bis[2-(4-aminophenoxy)-5-methyl-3-cyclohexylphenyl]methane,        bis[2-(4-aminophenoxy)-5-phenylphenyl]methane,        bis[2-(4-aminophenoxy)-3-methyl-5-phenylphenyl]methane,        1,1-bis[2-(4-aminophenoxy)-5-methylphenyl]methane,        1,1-bis[2-(4-aminophenoxy)-5-dimethylphenyl]ethane,        1,1-bis[2-(4-aminophenoxy)-5-methylphenyl]propane,        1,1-bis[2-(4-aminophenoxy)-3,5-dimethylphenyl]propane,        2,2-bis[2-(4-aminophenoxy)phenyl]propane,        2,2-bis[2-(4-aminophenoxy)-3,5-dimethylphenyl]propane,        1,1-bis[2-(4-aminophenoxy)-5-methylphenyl]butane,        2,2-bis[2-(4-aminophenoxy)-3,5-dimethylphenyl]butane,        1,1-bis[2-(4-aminophenoxy)-5-methylphenyl]-3-methylpropane,        1,1-bis[2-(4-aminophenoxy)-3,5-dimethylphenyl]cyclohexane, and        1,1-bis[2-(4-aminophenoxy)-5-methylphenyl]-3-3-5-trimethylcyclohexane,        and diaminosiloxane can be copolymerized.

But the materials are not limited to the above.

The examples of acid compounds having a long-chain alkylene radical andother copolymerizable compounds are as follows: octylsuccinicdianhydride, dodecylsuccinic dianhydride, octylmalonic dianhydride,decamethylenebistribenzenehexacarboxylic dianhydride,decamethylenebistrimethylenebistribenzenehexacarboxylic dianhydride,2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]octyltetracarboxylic dianhydride,2,2-bis[4-(3,4-dicarboxybenzoyloxy)phenyl]tridecanetetracarboxylicdianhydride,2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]tridecanetetracarboxylicdianhydride, stearic acid, stearylchloride, pyromellitic dianhydride,methylpyromellitic dianhydride, 3,3′,4,4′-biphenyltetracarboxylicdianhydride, dimethylenetribenzenehexacarboxylic dianhydride,3,3′,4,4′-biscyclohexanetetracarboxylic dianhydride,3,3′,4,4′-benzophenonetetracarboxylic dianhydride,3,3′,4,4′-diphenylmethanetetracarboxylic dianhydride,3,3′,4,4′-diphenylethertetracarboxylic dianhydride,3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride,2,3,6,7-naphtalenetetracarboxylic dianhydride,3,3′,4,4′-diphenylpropanetetracarboxylic dianhydreide, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propanetetracarboxylic dianhydride,2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropanetetracarboxylicdianhydride,2,2-bis[4-(3,4-dicarboxybenzoyloxy)phenyl]propanetetracarboxylicdianhydreide, cyclopentanetetracarboxylic dianhydride,1,2,3,4-cyclobutanetetracarboxylic dianhydride,bicyclo(2,2,2)octa-7-ene-2,3,5,6-tetracarboxylic dianhydride,1,2,3,4-cyclopentanetetracarboxylic dianhydride, and1,2,3,4-butanetetracarboxylic dianhydride.

Embodiment 3

FIGS. 4A and 4B illustrate a configuration of another embodiment of theliquid crystal display device according to the present invention. FIG.4A is a plan view of one of a plurality of pixels in a liquid crystaldisplay device of the so-called horizontal electric field type, FIG. 4Bis a cross-sectional view of the pixel of FIG. 1A taken along line b—bof FIG. 4A.

The pixels as illustrated in FIGS. 4A and 4B are arranged in the form ofa matrix to constitute a display area.

The embodiment illustrated in FIGS. 4A and 4B is similar to theembodiment illustrated in FIGS. 1A and 1B, except that a light-blockingfilm 15 made of the same material as the black matrix BM and having anarea larger than the spacer 10 is formed below and centered on thespacer 10 on the filter substrate 1B.

In connection with the embodiment illustrated in FIGS. 1A and 1B, it wasexplained that the orientation defects of the orientation film 11 causedby the spacer 10 can be masked by the counter-voltage signal line 4, butthere may be some cases in which it is impossible to predict what is thearea where the orientation defects occur, and therefore the object ofthis embodiment is to ensure the masking effect of the light-blockingfilm 15 by enlarging the masking area around the spacer 10 withoutproducing adverse effects on the aperture ratio of the pixel.

In the configuration of this embodiment, the light-blocking film 15 canbe formed simultaneously with the formation of the black matrix BM, andconsequently, it is advantageous that no additional manufacturing isneeded.

But it is needless to say that the light-blocking film 15 does not needto be formed of the same material as the black matrix BM.

Embodiment 4

FIG. 5 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a planview of one of a plurality of pixels in a liquid crystal display deviceof the so-called horizontal electric field type corresponding to FIG.1A.

The embodiment illustrated in FIG. 5 is similar to the embodimentillustrated in FIGS. 1A and 1B, except that the spacer 10 is located atthe intersection of the gate line 2 and the drain line 3 to cover theintersection. The reason why the spacer 10 is located at theintersection of the gate line 2 and the drain line 3 is that the liquidcrystal material is prevented from being present at the intersection sothat metal components of the drain line 3 is prevented from beingdissolved into the liquid crystal material due to electrochemicalreaction with the liquid crystal material serving as an electrolyte.

FIG. 6A is a plan view of the intersection of the gate line 2 and thedrain line 3 with the insulating film INS interposed therebetween, andFIG. 6B is a cross-sectional view of the intersection taken along lineb—b of FIG. 6A.

In FIG. 6B, in forming the protective film PAS over the intersection,the growth of the protective film PAS from over the top of theintersection interferes with that of the protective film PAS on theinsulating film INS at the intersection of the edges of long sides ofthe gate line 2 and the drain line 3 (i.e. at corners of theintersection), the protective film PAS cannot cover the intersectionsufficiently, and consequently, the liquid crystal material sometimespenetrates into the intersection and contacts the drain line 3 on theinsulating film INS. In such a case, it is inevitable that metalcomponents of the drain line 3 dissolve into the liquid crystal materialby the so-called galvanic corrosion.

It is for this reason that the spacer 10 is disposed so as to cover theintersection of the gate line 2 and the drain line 3 and preventpenetration of the liquid crystal material into the intersection in thisembodiment.

Considering the above-mentioned purpose of this embodiment, it is notalways necessary to cover the entire surface of the intersection, but itis sufficient to dispose the spacer 10 so as to cover at least theintersection of the edges of long sides of the gate line 2 and the drainline 3.

Embodiment 5

FIG. 7 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a planview of one of a plurality of pixels in a liquid crystal display deviceof the so-called horizontal electric field type corresponding to FIG.1A.

The embodiment illustrated in FIG. 7 is similar to the embodimentillustrated in FIG. 5, except that the spacer 10 is located at an areawhere the thin film transistor TFT is formed to cover the thin filmtransistor TFT.

In this embodiment, the spacer 10 covers the thin film transistor TFTsuch that at least corners of the drain electrode 3A or the sourceelectrode 5A of the thin film transistor TFT.

FIG. 8A is a plan view of the thin film transistor TFT, and FIG. 8B is across-sectional view of the thin film transistor TFT taken along lineb—b of FIG. 8A.

In FIG. 8B, in forming the protective film PAS over the top surface ofthe drain electrode 3A, the growth of the protective film PAS from overthe top surface of the drain electrode 3A interferes with that of theprotective film PAS on the insulating film INS at the corners of thedrain electrode 3A, the protective film PAS cannot cover the cornerssufficiently, and consequently, the liquid crystal material sometimespenetrates into the corners and contacts the drain electrode 3A. In sucha case, it is inevitable that metal components of the drain electrode 3Adissolve into the liquid crystal material by the so-called galvaniccorrosion.

The galvanic corrosion of the drain electrode 3A or the source electrode5A changes the width of the channel of the thin film transistor TFT, andconsequently, it is very advantageous that the galvanic corrosion can beprevented.

Incidentally, the semiconductor layer 6 forming the thin film transistorTFT can be considered as a conductive layer, and it may have a problemwith the gate line 2 similar to the problem explained in Embodiment 4,and consequently, it is very effective to dispose the spacer 10 to coverthe area where the thin film transistor TFT is formed.

Embodiment 6

FIG. 9 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a planview of one of a plurality of pixels in a liquid crystal display deviceof the so-called horizontal electric field type corresponding to FIG.1A.

The embodiment illustrated in FIG. 9 is similar to the embodimentillustrated in FIG. 5, except that the spacer 10 is located at theintersection of the counter-voltage signal line 4 and the drain line 3to cover the intersection.

The liquid crystal display device having this configuration prevents thegalvanic corrosion of the drain line 3 for the reason similar to that inEmbodiment 4.

This embodiment also provides an advantage of facilitating the controlof the thickness of the liquid crystal layer (the spacing between thetwo substrates) at the pixel because the spacer 10 is positionedapproximately at the center of the dimension of the pixel in the ydirection.

Embodiment 7

FIG. 10 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a planview of one of a plurality of pixels in a liquid crystal display deviceof the so-called horizontal electric field type corresponding to FIG.1A.

The embodiment illustrated in FIG. 10 is similar to the embodimentillustrated in FIG. 5, except that the spacer 10 is formed to cover oneof two electrodes forming a capacitor Cadd (an electrode extendingintegrally from the counter electrode 4), and thereby the area of thespacer 10 is made comparatively large.

The liquid crystal display device having this configuration prevents thegalvanic corrosion of the covered electrode by the liquid crystalmaterial as in the case of FIG. 9.

This embodiment can increase the area of the spacer 10 without noreduction in the aperture ratio of the pixel, and improve reliability ofthe spacer.

This embodiment also provides an advantage of facilitating the controlof the thickness of the liquid crystal layer (the spacing between thetwo transparent substrates) at the pixel because the spacer 10 ispositioned approximately at the center of the dimension of the pixel inthe y direction.

Embodiment 8

FIGS. 11A and 11B illustrate a configuration of another embodiment ofthe liquid crystal display device according to the present invention.FIG. 11A is a plan view of one of a plurality of pixels in a liquidcrystal display device of the so-called vertical electric field typesuch as the twisted nematic type, FIG. 11B is a cross-sectional view ofthe pixel of FIG. 11A taken along line b—b of FIG. 11A. The pixels asillustrated in FIGS. 11A and 11B are arranged in the form of a matrix toconstitute a display area.

In a liquid crystal display device of the vertical electric field type(commonly called the twisted nematic type), the transmission of light ateach pixel is controlled by a vertical electric field applied across alayer of liquid crystal material sandwiched between opposing transparentelectrodes formed on the inner surfaces of the opposing transparentsubstrates. Each pixel is formed by two electrodes formed on a pair ofopposing substrates, respectively. For the purpose of deviceconstruction and operation, U.S. Pat. No. 3,918,796, issued toFergasonon Nov. 11, 1975, is hereby incorporated by reference.

In the liquid crystal display device of the vertical field type, theconfigurations of the gate lines 2, the drain lines 3 and the thin filmtransistors TFT are approximately similar to those in theabove-explained liquid crystal display device of the horizontal electricfield type. The differences are that, in the liquid crystal displaydevice of the vertical electric field type, the pixel electrodes 5connected to the source electrode of the respective thin filmtransistors TFT are transparent films made of ITO (Indium-Tin-Oxide),for example, and are formed over the entire areas serving as theeffective pixel areas (at least areas surrounded by the black matrixBM).

The counter electrode 4A is formed on the filter substrate 1B to opposethe pixel electrodes 5 in common (sometimes called a common electrodefor this relationship) and is made of ITO, for example.

Light transmission through the liquid crystal layer is controlled byelectric fields generated in a direction approximately perpendicular tothe electrodes 5, 4A sandwiching the liquid crystal layer, and this isthe reason why the liquid crystal display device of this type is calleda liquid crystal display device of the vertical field type.

In this embodiment, the spacer 10 is formed on the filter substrate 1Bso as to oppose approximately the center of the pixel electrode 5.

As shown in FIG. 11B, the spacer 10 is formed on the planarizing film 8by shaping the synthetic resin film coated on the planarizing film 8using a photolithographic technique (and also by selective etching, ifnecessary) such that a truncated quadrilateral pyramid is left on theplanarizing film 8.

The counter electrode 4A and the orientation film 11 are coated on theplanarizing film 8 including the spacer 10 sequentially. The orientationfilm 11 formed on the side wall of the spacer 10 is not parallel withthe orientation film 7 formed on the TFT substrate 1A.

In other words, the configuration is such that, in the majority of thepixel area, electric fields are generated perpendicularly to the majorsurfaces of the substrates, but in the vicinity of the spacer 10electric fields are generated in a direction at an angle from the normalto the major surfaces as shown in FIG. 11B, and this provides theabove-explained multi-domain effect.

This multi-domain effect eliminates the problem that the reversal intransmitted light intensity through the liquid crystal layer occurs atviewing angles deviating considerably from the main anticipated viewingangle of the liquid crystal panel due to the angular dependence of theelectro-optic characteristics of the liquid crystal layer.

This advantage is obtained by forming the spacer 10 within the effectivepixel area (an area surrounded by the black matrix BM) without the needfor increasing the number of the manufacturing steps.

In this embodiment, one spacer is disposed in each pixel, but thepresent invention is not limited to this arrangement.

As shown in FIGS. 12A and 12B corresponding to FIGS. 11A and 11B,respectively, the present invention can be configured such that threespacers 10 are arranged along the long sides of the pixel.

The above advantage is further improved by employing liquid crystalmaterial of negative dielectric anisotropy.

Embodiment 9

FIGS. 13A and 13B illustrate a configuration of another embodiment ofthe liquid crystal display device according to the present invention.FIG. 13A is a plan view of one of a plurality of pixels in a liquidcrystal display device of the so-called vertical electric field typesuch as the twisted nematic type, FIG. 13B is a cross-sectional view ofthe pixel of FIG. 13A taken along line b—b of FIG. 13A. FIGS. 13A and13B correspond to FIGS. 11A and 11B, respectively.

The embodiment illustrated in FIGS. 13A and 13B is similar to theembodiment illustrated in FIGS. 11A and 11B, except that the pixelelectrode 5 formed on the substrate opposing the substrate having thespacer 10 formed thereon is formed with an opening 5 h facing the spacer10.

The opening 5 h in the pixel electrode 5 is centered on the top surfaceof the spacer 10 and is larger in area than the top surface of thespacer 10. This configuration prevents unexpected short circuit betweenthe pixel electrode 5 and the counter electrode 4A occurring even if theorientation films 11, 7 are interposed therebetween.

This means that it is sufficient that the pixel electrode 5 isconfigured so as to be absent at an area facing the spacer 10, andtherefore the configuration of the present invention is not limited tothe opening, but the configuration such as a cutout can also beemployed. The similar configurations can be employed even if a pluralityof spacers 10 are arranged in a pixel.

For example, as shown in FIGS. 14A and 14B corresponding to FIGS. 12Aand 12B, respectively, three openings are provided in three portionsfacing the three spacers 10, respectively, of the pixel electrode 5.

Embodiment 10

FIG. 15 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a planview of one of a plurality of pixels in a liquid crystal display deviceof the so-called vertical electric field type such as the twistednematic type.

This embodiment aims at heightening the multi-domain effect, and thespacer formed within one pixel area is configured so as to have aportion extending along the long sides of the pixel area and portionsextending along the short sides of the pixel area. The spacer of thisconfiguration has the shape extending along respective directions, andthereby increases the area capable of producing the multi-domain effectand heightens the multi-domain effect.

In this embodiment, as shown in FIGS. 15 and 16, in each of two regionsobtained by subdividing the pixel area in horizontal and verticaldirections, the spacer is shaped to be symmetrical so that the regionsfor producing the multi-domain effect are distributed uniformly over theentire pixel, and consequently, the quality of displayed images can beimproved.

Incidentally, it is sometimes sufficient that, instead of subdividingthe pixel area both in horizontal and vertical directions, in each oftwo regions obtained by subdividing the pixel area in a horizontal orvertical direction, the spacer is shaped to be symmetrical.

By extending the above-described spacers so as to pass throughapproximately the center of the pixel area, the control of the thicknessof the liquid crystal layer is facilitated.

Embodiment 11

FIGS. 17A and 17B illustrate a configuration of another embodiment ofthe liquid crystal display device according to the present invention.FIG. 17A is a plan view of one of a plurality of pixels in a liquidcrystal display device of the so-called vertical electric field typesuch as the twisted nematic type, FIG. 17B is a cross-sectional view ofthe pixel of FIG. 17A taken along line b—b of FIG. 17A. FIGS. 17A and17B correspond to FIGS. 11A and 11B, respectively.

The embodiment illustrated in FIGS. 11A and 11B takes advantage of theso-called multi-domain effect, but the present embodiment aims atmasking the domains.

The light-blocking film 15 is formed on the filter substrate 1B havingthe spacer 10 formed thereon such that the light-blocking film 15 iscentered on the bottom surface of the spacer 10 and is larger in areathan the bottom surface of the spacer 10. The light-blocking film 15 ismade of the same material as the black matrix BM and is formedsimultaneously with the black matrix BM.

FIG. 18A is a plan view of a modification of the present embodiment, andFIG. 18B is a cross-sectional view of the pixel of FIG. 18A taken alongline b—b of FIG. 18A. This modification aims at masking the domainsoccurring around the spacer 10 by light-blocking films 17 formed on theTFT substrate 1A so as to ensure reliability.

The light-blocking film 17 formed on the TFT substrate 1A is made of ametallic layer in this modification, and is formed of the same materialas the gate line 2 and simultaneously with the gate line 2, for example.

In this modification, the light-blocking film 17 is annular so as tomask light from the side wall of the spacer 10, but it is not alwayslimited to such a shape, and the light-blocking film 17 of the sameshape as the light-blocking film 15 can be employed.

It may sometimes be sufficient to form the light-blocking films againstthe domains caused by the spacer on the TFT substrate 1A only.

Embodiment 12

FIG. 19 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a planview of the spacer 10 employed in this embodiment. The spacer 10 of thisembodiment can be employed as the spacers in the previous embodimentsand other liquid crystal display devices.

In FIG. 19, the spacer 10 is of the truncated quadrilateral pyramidalshape having a large-area base on the substrate side thereof and asmall-area top surface 10A. That is to say, the spacer 10 is flaring andhas tapering side walls.

The spacer 10 is provided with a cutout 10C which extends on a side wallfrom the center of one of four sides of its top surface 10A to thecenter of a corresponding one of four sides of its base.

The following is the reason for this configuration of the spacer 10.

As shown in FIG. 20, a recess 10D is sometimes formed at the centralportion of the top surface 10A of the spacer 10. The recess 10D may beformed by shrinkage when the spacer is cured or due to indentation inthe substrate having the spacer formed thereon.

Air is sealed in the recess 10D when the spacer having the recess 10D onone substrate is pressed against the other substrate to assemble theliquid crystal panel, and the air is difficult to evacuate in theoperation of filling the liquid crystal material into the space betweenthe two substrates.

After the liquid crystal material is sealed in the liquid crystal panel,the air penetrates into the liquid crystal layer in the form of bubblesdue to vibrations or shocks and changes the specific resistance of theliquid crystal material.

This embodiment aims at evacuating completely the air easily containedbetween the top surface 10A of the spacer 10 and the other substrateagainst which the top surface 10A is pressed, by providing the cutout 10c in the spacer 10 as explained in connection with FIG. 20. That is tosay, the cutout 10C serves as means for evacuating the air from therecess 10D and as a path for the liquid crystal material to penetrateinto the recess 10D.

For this object, it is not always necessary that means for evacuatingthe air is in the form of the cutout 10C of the above configuration, butmeans for evacuating the air may be in the form of a groove orindentation formed in the top surface 10A of the spacer 10, for example,or in the form of a groove or indentation traversing the top surface10A.

The shape of the spacer 10 is not limited to the above configuration,but it may be a circle or others in a plan view.

Embodiment 13

FIG. 21 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is afragmentary perspective view of the spacer 10 and its vicinity in thisembodiment.

This embodiment aims at evacuating the air between the spacer 10 and thesubstrate against which the spacer is pressed as in Embodiment 12, andin this embodiment the substrate pressed against the spacer 10 isconfigured for the object.

As shown in FIG. 21, a groove or indentation 15 is formed in a portionof the protective film PAS on the substrate which is pressed against thespacer 10 such that the groove or indentation extends beyond the contactarea between the spacer 10 and the protective film PAS.

In this embodiment, the groove or indentation 15 serves as means forevacuating the air contained between the top surface 10A of the spacer10 and the substrate against which the top surface 10A is pressed.

Embodiment 14

FIG. 22 is a plan view of another embodiment of the liquid crystaldisplay device according to the present invention.

In FIG. 22, a filling hole 21 for the liquid crystal material isprovided in a sealing member 20 for sealing the liquid crystal materialbetween the substrates 1A and 1B, and the means for evacuating the airas explained in the previous embodiments is provided in the spacer 10disposed in an area enclosed by the sealing member 20 or in thesubstrate against which the spacer 10 is pressed.

The exit for the air of the means for evacuating the air, the cutout 10c, for example, is directed toward the filling hole 21 for the liquidcrystal material.

This configuration enables efficient evacuation of the air containedbetween the spacer 10 and the substrate against which the spacer 10 ispressed, via the above-explained means for evacuating the air, becausethe filling hole 21 for the liquid crystal material serves as the exitfor evacuating air from the space between the two substrates as well asthe hole for filling the liquid crystal material into a space betweenthe two substrates, and consequently, the air contained between thespacer 10 and the substrate is directed directly into the filling hole21 without going around the spacer 10.

Embodiment 15

FIG. 23 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is aperspective view of the spacer 10 in this embodiment.

As shown in FIG. 23, the spacer 10 is subdivided into plural spacerpieces, and in other words, the spacer 10 comprises a group ofsubdivided spacers.

The spacer 10 having this configuration has a function of evacuating theair as in the previous embodiments, and also is provided withresiliency.

It is inevitable that the spacer 10 is subject to strong force appliedby the substrate, but the spacer 10 can prevent its breakage with itsresiliency.

For this object, it is sufficient that the subdivision of the spacer 10is applied to at least the top portion of the spacer 10 as shown in FIG.24.

Embodiment 16

FIG. 25 illustrates a configuration of another embodiment of the liquidcrystal display device of the horizontal electric field type accordingto the present invention, and is a cross-sectional view of the liquidcrystal display device taken along one of its gate lines. The spacers 10are fixed on the filter substrate 1B opposing the TFT substrate 1A, andcomprise a first type of spacers 10B disposed in a region 25B in FIG. 25for maintaining the spacing between the two substrates 1A, 1B and asecond type of spacers 10A disposed so as to be superposed on both theends of each of the gate lines in a region 25A in FIG. 25.

A plurality of strip-shaped conductive layers 21 are formed on thesurface of the filter substrate 1B facing toward the liquid crystallayer such that each of the strip-shaped conductive layers 21 issuperposed on a respective one of the gate lines 2 formed on the TFTsubstrate 1A, and consequently, each of the strip-shaped conductivelayers 21 covers a pair of the second type of spacers 10A correspondingto one of the gate lines 2 and is electrically connected with thecorresponding one of the gate lines 2.

This configuration provides a redundant circuit for each of the gatelines 2 and provides protection against unintentional line breaks in thegate lines 2.

In this embodiment, the redundant circuits are provided to the gatelines 2, the above configuration is also applicable to protectionagainst the line breaks in the drain lines 3 by interchanging the gateline 2 with the drain line 3 in FIG. 25.

This embodiment is also applicable to the previous embodiments of theliquid crystal display device of the horizontal electric field type.

Embodiment 17

FIG. 26 illustrates a configuration of another embodiment of the liquidcrystal display device of the vertical electric field type according tothe present invention, and is a cross-sectional view of the liquidcrystal display device taken along one of the gate lines 2. The spacers10 are fixed on the filter substrate 1B opposing the TFT substrate 1A,and comprise a first type of spacers 10B disposed in a region 26B inFIG. 26 for maintaining the spacing between the two substrates 1A, 1Band a third type of spacers 10A disposed in the vicinity of the sealingmember 20 for sealing the two substrates 1A, 1B in a region 26A in FIG.26.

The third type of spacers 10A are formed simultaneously with the firsttype of spacers 10B. A common electrode (a transparent electrode) 22facing the plural pixels in common is formed on the surface of thefilter substrate 1B facing toward the liquid crystal layer including thesurfaces of the spacers 10. A conductive layer 23 is formed on a regionof the TFT substrate 1A against which the third type spacer 10A ispressed, such that the conductive layer 23 covers the third type spacer10A and is electrically connected with the common electrode 22.

The conductive layer 23 extends beyond the sealing member 20 on the TFTsubstrate 1A so as to be connected to a terminal for supplying areference voltage to the common electrode 22. The reference voltagesupplied to the terminal on the TFT substrate 1A is applied to thecommon electrode 22 on the filter substrate 1B via the third type spacer10A.

The liquid crystal display device of this configuration eliminates theneed for providing an additional connecting means for bringing out theconnection of the common electrode 22 onto the surface of the TFTsubstrate 1A.

The present embodiment is also applicable to the previous embodiments ofthe liquid crystal display device of the vertical electric field type.

Embodiment 18

In the previous embodiments, spacers are fixed on the TFT substrate orthe filter substrate.

It is preferable to fix the spacers on the filter substrate especiallywhen it is necessary to prevent degradation of characteristics of thethin film transistors, because fixation of the spacers on the TFTsubstrate requires an additional process step of selective etching forforming the spacers by a photolithographic technique, and chemicals usedin the etching process may cause deterioration of the thin filmtransistors.

It is preferable to fix the spacers on the TFT substrate when it isnecessary to register the spacers accurately with the TFT substrate.When the spacers are fixed on the filter substrate, registration errorsoccur in superposing the filter substrate on the TFT substrate andconsequently, the spacers cannot sometimes be registered accurately withthe TFT substrate.

Embodiment 19

FIG. 27 is a detailed cross-sectional view of the spacer 10 fabricatedon and fixed to the filter substrate 1B.

The black matrix BM and the color filter FIL are formed on the surfaceof the filter substrate 1B on the liquid crystal layer side thereof, andthen the planarizing film 8 made of thermosetting resin is formed on theblack matrix BM and the color filter FIL for planarizing the top surfaceof the filter substrate 1B. The spacer 10 made of photocuring resin ispositioned at a predetermined position on the planarizing film 8.

Fabrication of the spacer 10 by using photocuring resin eliminates theneed for the process step of selective etching, resulting in thereduction of the number of the process steps.

This embodiment is also applicable to the previous embodiments. Thisembodiment is not limited to fabrication of the spacers on the filtersubstrate 1B, but also is applicable to fabrication of the spacers onthe TFT substrate 1A.

Embodiment 20

FIG. 28A is a plan view of the arrangement of the spacers 10 superposedon the black matrix BM for defining the contours of the pixels in thedisplay area. The spacers 10 are distributed uniformly over the entiredisplay area, and each of the spacers 10 is allotted to a groupcomprising the equal number of adjacent pixels. The number of thespacers 10 disposed in the display area is reduced so as to reduce theorientation defects caused by the spacers 10. This prevents occurrenceof unintentional contrast produced by light leakage, especially indisplaying of a black image.

Embodiment 21

FIG. 28B is a plan view of the arrangement of the spacers 10 superposedon the black matrix BM in the display area. The number of the spacers 10disposed in the display area is reduced as in Embodiment 20, but thedifference is that spacers are arranged randomly, instead of beingarranged uniformly.

The repeating pattern of light leakage is easily discernible to thehuman eye, and therefore the problem with the light leakage is solved byarranging the spacers randomly.

Embodiment 22

FIG. 29 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a viewsimilar to that of FIG. 1B.

In FIG. 29, the spacer 10 is fixed to the substrate 1B and the substrate1A is superposed on the substrate 1B, and an adhesive 30 is interposedbetween the spacer 10 and a region of the transparent substrate 1Aagainst which the spacer 10 is pressed.

Suppose the adhesive 30 is not interposed between the spacer 10 and thesubstrate 1A, then, in the contact area between the spacer 10 and thesubstrate 1A, both the surfaces of the spacer 10 and the substrate 1Aare covered with the orientation films made of the same material,respectively, and there arises a problem that adhesion between the twosurfaces is weak.

In this embodiment, by employing the adhesive 30, a Si coupling agent,for example, the reliability in maintaining the spacing between the twosubstrates is secured.

The following explains an example of a method of manufacturing theliquid crystal display device of this configuration by reference toFIGS. 30A to 30E.

STEP 1

As shown in FIG. 30A, fabricate spacers 10 on the substrate 1B and thencoat an orientation film (not shown) on the surface of the substrate 1Bincluding the surfaces of the spacers 10.

STEP 2

As shown in FIG. 30B, bring the top surfaces of the spacers 10 intocontact with the surface of the adhesive agent 30 in a container.

STEP 3

As shown in FIG. 30C, the substrate 1B with the surfaces of the spacers10 coated with the adhesive agent 30 is obtained.

STEP 4

As shown in FIG. 30D, superpose the substrate 1B on the other substrate1A.

STEP 5

AS shown in FIG. 30E, cure the adhesive agent 30 by heating it so thatthe spacers are fixed to each of the two substrates 1A, 1B.

The following explains another example of a method of manufacturing theliquid crystal display device of the above configuration by reference toFIGS. 31A to 31E.

STEP 1

As shown in FIG. 31A, fabricate spacers 10 on the substrate 1B and thencoat an orientation film (not shown) on the surface of the substrate 1Bincluding the surfaces of the spacers 10.

STEP 2

As shown in FIG. 31B, place a roller 31 between the substrate 1B and thesurface of the adhesive agent 30 in a container such that the surface ofthe roller 31 contacts both the spacer 10 and the surface of theadhesive agent 30, then apply the adhesive agent 30 on the top surfacesof the spacers 10 by rotating the roller 31.

STEP 3

As shown in FIG. 31C, the substrate 1B with the surfaces of the spacers10 coated with the adhesive agent 30 is obtained.

STEP 4

As shown in FIG. 31D, superpose the substrate 1B on the other substrate1A.

STEP 5

As shown in FIG. 31E, cure the adhesive agent 30 by heating it so thatthe spacers are fixed to each of the two substrates 1A, 1B.

This embodiment is also applicable to the previous embodiments.

Embodiment 23

FIG. 32 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention, and is a viewsimilar to that of FIG. 1B.

As shown in FIG. 32, a recess 40 is formed on the substrate 1A opposingthe substrate 1B having the spacer 10 fixed thereto such that the top ofthe spacer 10 is driven into the recess 40. The recess 40 is formed inthe protective film PAS on the TFT substrate 1A, for example, and has aflaring cross section. With this configuration, the top of the spacer 10is forced into the recess 40 and is fastened tightly to the TFTsubstrate 1A as bonded with an adhesive agent.

FIG. 33 illustrates a configuration of another embodiment of the liquidcrystal display device according to the present invention. A groovecorresponding to the recess 40 in FIG. 32 is formed by a pair of signallines (or wiring lines) 42. The opposing side walls of the two signallines are tapered in the opposite directions.

The configuration of this embodiment is such that the top of the spacer10 is forced into the recess, but the present invention is not limitedto this configuration.

The similar beneficial effects are obtained even if the spacer 10 andthe recess or groove are configured such that the spacer 10 fits looselyinto the recess or groove. This configuration does not serve to preventvariations in the spacing between the two opposing substrates (thesealing member prevents these variations), but can prevent the lateralalignment errors between the two opposing substrates.

This combination of the spacer 10 and the recess or the groove alsoserves as means for aligning the opposing two substrates with eachother.

As is evident from the above explanation, the liquid crystal displaydevice according to the present invention can improve the quality ofdisplayed images.

1. A liquid crystal display device comprising: first and secondsubstrates, a liquid crystal layer sandwiched between the first andsecond substrates; a pixel electrode formed on the first substrate; acounter electrode formed on the second substrate; and a projectionformed on one of first and second substrates, wherein the projection hasa body and first, second, third and fourth branches, the first, second,third and fourth branches are shorter than the body and extend in adirection perpendicular to a direction of extension of the body, thefirst and second branches extend is opposite directions from each other,and the third and fourth branches extend in opposite directions fromeach other.
 2. A liquid crystal display device according to claim 1wherein the first and second branches are substantially equal in lengthto each other.
 3. A liquid crystal display device according to claim 2,wherein the third and fourth branches are substantially equal in lengthto each other.
 4. A liquid crystal display device according to claim 3,wherein the first, second, third and fourth branches are substantiallyequal to each other.
 5. A liquid crystal display device according toclaim 3, wherein the first, second, third and fourth branches are inparallel with each other, and the third and fourth branches are inparallel with each other.
 6. A liquid crystal display device accordingto claim 1, wherein the first, second, third and fourth branches are inparallel with each other, and the third and fourth branches are inparallel with each other.
 7. A liquid crystal display device comprising:first and second substrates, a liquid crystal layer sandwiched betweenthe first and second substrates; a pixel electrode formed on the firstsubstrate; a counter electrode formed on the second substrate; and amulti-domain-effect-producing element formed on one of the first andsecond substrates, wherein the multi-domain-effect-producing element hasa body and first, second, third and fourth branches, the first, second,third and fourth branches are shorter than the body, the first and thirdbranches extend in a direction perpendicular to a direction of extensionof the body, the first and second branches extend in opposite directionsfrom each other, and the third and fourth branches extend in oppositiondirections from each other.
 8. A liquid crystal display device accordingto claim 7, wherein the first, second, third and fourth branches aresubstantially equal in length to each other.
 9. A liquid crystal displaydevice according to claim 8, wherein the first, second, third and fourthbranches are substantially equal in length to each other.
 10. A liquidcrystal display device according to claim 9, wherein the first, second,third and fourth branches are substantially equal to each other .
 11. Aliquid crystal display device according to claim 9, wherein the first,second, third and fourth branches are in parallel with each other, andthe third and fourth branches are in parallel with each other.
 12. Aliquid crystal display device according to claim 7, wherein the first,second, third and fourth branches are in parallel with each other, andthe third and fourth branches are in parallel with each other.